Long-established industries in rural areas are now creating noise issues for new communities that have developed nearby. Proactive control of noise emission has therefore become a priority for industries concerned with respecting the tranquillity of residents. The traditional method of noise monitoring utilizes a sound level meter (SLM) which must be installed to areas of interest by trained and experienced personnel. Since a class 1 SLM is relatively expensive, long-term monitoring of large areas can hardly be considered. In this paper, we discuss the practical implementation of a stand-alone MEMS-based SLM capable of recording one-minute time samples and wirelessly transmitting sound level values in third octave bands in the range from 20 Hz to 8 kHz, every 15 minutes. The current prototype uses a digital MEMS microphone with I2S interface connected to an Arduino MKR WiFi 1010 microcontroller for an overall cost of less than 100 CHF. Technical choices for the implementation of the prototype as well as a benchmark with a class 1 SLM are discussed in this paper.